Field
Exemplary embodiments relate to a display substrate, and a method of fabricating the same. More particularly, exemplary embodiments relate to reducing the number of masks from five (5) to four (4) when fabricating the display substrate used in a liquid crystal display device in a horizontal field (Plane to Line Switching (PLS)) mode.
Discussion of the Background
In general, a liquid crystal display device includes a display substrate comprising a switching element and a pixel electrode, an opposing substrate opposite to the display substrate, and a liquid crystal layer interposed between the display substrate and the opposing substrate. The liquid crystal display device displays an image by applying different levels of voltages to the liquid crystal layer and controlling the light transmittance.
The liquid crystal display device may be divided into a vertical field mode and a horizontal field mode according to the direction of the electric field.
Currently, liquid crystal display devices operated using a vertical field mode have problems with wide angle viewing, which led to active development of liquid crystal display devices operated using horizontal field mode. Particularly, research for reducing manufacturing costs of a liquid crystal display device operated in a Plane to Line Switching (PLS) mode, which is an example of the horizontal field mode, is being conducted.
The display substrate includes a plurality of thin film patterns formed by patterning a thin film formed on an insulating substrate through a photolithography process. Each of the thin film patterns may be formed by forming a photo-resistant pattern on the thin film, and etching the thin film by using the photo-resistant pattern as an etch mask. The photolithography process may be performed by dry etching or wet etching according to the properties of the thin film. When the thin film includes metal, it may generally be patterned by using a composition of etchants, and when the thin film is an insulating layer, including a silicon oxide and the like, it may generally be patterned by using etching gas.
In order to form one thin film pattern, a mask including a design of the thin film pattern is used. In order to minimize the use of a high-priced mask or to simplify a process, two or more thin films may be patterned by using one mask. However, even when one mask is used, when properties of the thin films are different from each other, the etching process must be performed using different methods. So it is not easy to substantially decrease the number of process steps.
Accordingly, the present disclosure shows a method of decreasing a five mask (M) processes to a four mask (M) processes, which will be described in detail herein.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.